For years, astronomers straggled to calculate the age of the universe. Estimates ranged from 10 to 20 billion years old, a frustratingly large spread. But that was before the launch of the Hubble Space Telescope, named after the astronomer whose discovery 70 years ago began the quest to learn the universe’s age.
Edwin Hubble found that the galaxies (星系) within the universe are speeding away from each other at a rate proportional to their distance. That expansion rate----the Hubble constant (常数)----is the key to calculating the age and size of the universe. But pinning down the constant requires precise measurements of the distances to far-flung galaxies.
In May, a team led by Wendy Freeman of the Carnegie Institution, of Washington, D. C., announced the result of eight years of Hubble measurements: The universe is expanding at a rate of 21 kilometers per million light-years. That translates to an age of approximately 12 billion years for the universe. simila
A. Approximately 10 billion years old.
B. 20 billion years old.
C. Approximately 12 billion years old.
D. Not quite accurate now.
For years, astronomers straggled to calculate the age of the universe. Estimates ranged from 10 to 20 billion years old, a frustratingly large spread. But that was before the launch of the Hubble Space Telescope, named after the astronomer whose discovery 70 years ago began the quest to learn the universe’s age.
Edwin Hubble found that the galaxies (星系) within the universe are speeding away from each other at a rate proportional to their distance. That expansion rate----the Hubble constant (常数)----is the key to calculating the age and size of the universe. But pinning down the constant requires precise measurements of the distances to far-flung galaxies.
In May, a team led by Wendy Freeman of the Carnegie Institution, of Washington, D. C., announced the result of eight years of Hubble measurements: The universe is expanding at a rate of 21 kilometers per million light-years. That translates to an age of approximately 12 billion years for the universe. simila
A. Estimates of the universe’s age range from 10 to 20 billion years old, a frustratingly large spread.
B. The quest to learn the universe’s age began 70 years ago by a famous astronomer named Edwin Hubble.
C. The galaxies in the universe stand still, relative to each other.
D. The new number of the universe’s age is not quite the last value.
Virtually everything astronomers know about objects outside the solar system is based on the detection of photons-quanta of electromagnetic radiation. Yet there is another form of radiation that permeates the universe: neutrinos. With (as its name implies) no electric charge, and negligible mass, the neutrino interacts with other particles so rarely that a neutrino can cross the entire universe, even traversing substantial aggregations of matter, without being absorbed or even deflected. Neutrinos can thus escape from regions of space where light and other kinds of electromagnetic radiation are blocked by matter. Not a single, validated observation of an extraterrestrial neutrino has so far been produced despite the construction of a string of elaborate observatories, mounted on the earth from Southern India to Utah to South Africa. However, the detection of extraterrestrial neutrinos are of great significance in the study of astronomy. Neutrinos carry with Their information abou
A. get through,
B. pass by.
C. interact with.
D. derive from.
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